It is customary to transport a load on a vehicle, such as a ship, railroad car, or tractor-trailer, in a closed container of standard size and dimension. Typically, these containers are releasably attached to the vehicle by releasable locking mechanisms referred to as “twistlocks.” Twistlocks are standardized for engagement with fittings built into one or more corners of the container.
Oftentimes, the floor to which the container is to be affixed is cambered. For example, some trailers are flatbed trailers, and are sometimes cambered in order to bear the heavy loads that are sometimes placed upon them. When a shipping container is placed upon a cambered flatbed trailer, it can be unstable because the bottom of the container does not make contact at every point along the trailer. This instability sometimes leads to unsafe hauling conditions or otherwise causes the cargo inside the container to shift in transit. When cambered flatbed trailers are used to transport shipping containers, they are sometimes modified to prevent uneven distribution, and such modifications can be both expensive and time consuming.